Automatically switching different aspiration levels and/or pumps to an ocular probe

ABSTRACT

Methods and apparatuses for automatically switching different aspiration levels to an ocular probe are disclosed herein. The probe may be a phacoemulsification probe. A first aspiration level, supplied by a first pump, may be applied to the probe simultaneously with ultrasonic energy. A second aspiration level, supplied by a second pump, may be automatically switched from the first aspiration level. Control feed back of the pumps may be varied according to set thresholds.

This application is a divisional of and claims priority to U.S.application Ser. No. 12/614,093, filed on Nov. 6, 2009, which claimspriority to U.S. Application No. 61/198,626 filed on Nov. 7, 2008, theentirety of which are hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates generally to the field of surgery, andmore specifically to devices, systems, and methods for treatment of aneye. Exemplary embodiments allow enhanced treatment to structures withinan eye by at least once (though more commonly repeatedly or evencyclically) applying different levels and/or types of aspiration to anocular probe, often such that the aspiration changes during a treatmentof a particular eye.

BACKGROUND OF THE INVENTION

The present invention is generally related to methods, devices, andsystems for controlling surgical fluid flows, particularly duringtreatment of an eye. In exemplary embodiments, the invention removesmaterial from within the eye in part by a displacement-inducedaspiration flow (such as that caused by a peristaltic or other positivedisplacement pump), and in part by a vacuum-induced aspiration flow(such as that caused by a venturi pump). Optionally, the aspiration flowmay switch between a displacement pump and a venturi pump while materialis being fragmented and removed from within the eye. While the systemoperator will typically have control over the overall mode of operationthroughout a procedure, switching between these two different types ofaspiration flow may occur “on-the-fly” without halting of acorresponding irrigation flow, and without awaiting input from thesystem operator regarding that particular flow change. The material maybe removed from an anterior or posterior chamber of the eye, such as forphacoemulsification of cataracts, treatment of retinal diseases,vitrectomy, and the like.

The optical elements of the eye include both a cornea (at the front ofthe eye) and a lens within the eye. The lens and cornea work together tofocus light onto the retina at the back of the eye. The lens alsochanges in shape, adjusting the focus of the eye to vary between viewingnear objects and far objects. The lens is found just behind the pupil,and within a capsular bag. This capsular bag is a thin, relativelydelicate structure which separates the eye into anterior and posteriorchambers.

With age, clouding of the lens or cataracts is fairly common. Cataractsmay form in the hard central nucleus of the lens, in the softerperipheral cortical portion of the lens, or at the back of the lens nearthe capsular bag.

Cataracts can be treated by the replacement of the cloudy lens with anartificial lens. Phacoemulsification systems often use ultrasound energyto fragment the lens and aspirate the lens material from within thecapsular bag. This may allow the remaining capsular bag to be used forpositioning of the artificial lens, and maintains the separation betweenthe anterior portion of the eye and the vitreous humour in the posteriorchamber of the eye.

During cataract surgery and other therapies of the eye, accurate controlover the volume of fluid within the eye is highly beneficial. Forexample, while ultrasound energy breaks up the lens and allows it to bedrawn into a treatment probe with an aspiration flow, a correspondingirrigation flow may be introduced into the eye so that the total volumeof fluid in the eye does not change excessively. If the total volume offluid in the eye is allowed to get too low at any time during theprocedure, the eye may collapse and cause significant tissue damage.Similarly, excessive pressure within the eye may strain and injuretissues of the eye.

While a variety of specific fluid transport mechanisms have been used inphacoemulsification and other treatment systems for the eyes, aspirationflow systems can generally be classified in two categories: 1)volumetric-based aspiration flow systems using positive displacementpumps; and 2) vacuum-based aspiration systems using a vacuum source,typically applied to the aspiration flow through an air-liquidinterface. Among positive displacement aspiration systems, peristalticpumps (which use rotating rollers that press against a flexible tubingto induce flow) are commonly employed. Such pumps provide accuratecontrol over the flow volume. The pressure of the flow, however, is lessaccurately controlled and the variations in vacuum may result in thefeel or traction of the handpiece varying during a procedure.Peristaltic and other displacement pump systems may also be somewhatslow for some procedures. Vacuum rise times tend to be slower forperistaltic systems than venturi systems. This may result in an overallsluggish feel to the surgeon. Moreover, the ultrasonic vibrations of aphacoemulsification tip may (despite peristaltic aspiration flow intothe tip) inhibit the desired fragmentation-inducing engagement betweenthe tip and tissue particles.

Vacuum-based aspiration systems provide accurate control over the fluidpressure within the eye, particularly when combined with gravity-fedirrigation systems. While vacuum-based systems can (in somecircumstances) result in excessive fluid flows, they may have advantageswhen, for example, it is desired to bring tissue fragments to the probe,or when removing a relatively large quantity of the viscous vitreoushumour from the posterior chamber of the eye. Unfortunately, venturipump and other vacuum-based aspiration flow systems are subject topressure surges during occlusion of the treatment probe, and suchpressure surges may decrease the surgeon's control over the eyetreatment procedure. Displacement pump systems are similarly subject tovacuum spikes during and immediately following occlusion of the probe.

While there have been prior proposals for multiple pump systems whichmake use of either a positive displacement pump or a vacuum source, thepreviously proposed systems have not been ideal. Hence, to providesurgeons with the benefits of both vacuum-based and displacement-basedaspiration flows, still further improvements appear desirable. Inparticular, interrupting a procedure to switch between aspirationsystems may be inconvenient, and it may be difficult or even impossibleto take full advantage (for example) of the full potential of combiningboth vacuum-based and displacement-based aspiration flows using prioreye treatment systems.

In light of the above, it would be advantageous to provide improveddevices, systems, and methods for eye surgery. It would be particularlyadvantageous if these improvements allowed system users to maintain thebenefits of vacuum and/or displacement fluid control systems whenappropriate, and without having to interrupt the procedure to manuallyswitch pumps, change handpieces or other system components, or the like.Ideally, these improved systems would provide benefits beyond those ofperistaltic or venturi systems alone, such as combinationperistaltic/venturi systems, without delaying the procedure orincreasing the complexity of the operation to the system operator.

BRIEF SUMMARY OF THE INVENTION

One embodiment of the invention may include a method for applyingaspiration to a probe. The method may be computer implemented. Themethod may include applying a base vacuum level from a first pump to aprobe to achieve a base level flow-rate, applying a secondary vacuumlevel from a second pump to the probe to achieve an additive levelflow-rate, which is additional to the base level flow-rate, anddetecting that the probe is at least partially occluded by detecting anincreased secondary vacuum level.

Another embodiment of the invention may include a method for removingmaterial from an eye. The method may include generating a base levelaspiration flow by applying a base aspiration pressure differentialusing a pressure pump to an aspiration flow pathway from the eye,generating an additive level flow, during the base level flow, bypumping the additive level flow with a volumetric pump, and detectingocclusion of the aspiration flow pathway by detecting an increasedpressure differential above the base pressure differential generated bythe volumetric pump.

Yet another embodiment of the invention may include a system forremoving material from within an eye. The system may include a probehaving a distal tip insertable into the eye, wherein the tip comprisesan aspiration port, and a console coupled with/to the port along anaspiration pathway, wherein the console comprises a processor and a pumpsystem for providing a base level aspiration flow by applying a baseaspiration pressure differential and an additive level flow, during thebase level flow, wherein the processor is configured to detect occlusionof the aspiration flow pathway by detecting an increased pressuredifferential above the base pressure. The pump system may comprisemultiple pumps, including a first pump and a second pump, wherein thefirst pump and the second pump may be a vacuum based (pressure) pumpand/or a flow based (volumetric) pump.

Yet another embodiment of the invention may include a method forapplying aspiration and irrigation to a phacoemulsification device. Themethod may be computer implemented. The method may include applying alow flow-rate aspiration from a first pump to an aspiration port of aprobe, applying a low flow-rate irrigation from a fluid source to anirrigation port of the probe while applying the low flow-rateaspiration, transitioning from the low flow rate aspiration to a highflow-rate aspiration from a second pump to the aspiration port, andtransitioning from the low flow-rate irrigation to a high flow-rateirrigation while transitioning from the low flow-rate aspiration to thehigh flow-rate aspiration.

Yet another embodiment of the invention may include a system forremoving material from within an eye. The system may include a probehaving a distal tip insertable into the eye, wherein the tip comprisesan aspiration port and an irrigation port, and a console coupled with/tothe port along an aspiration pathway, wherein the console comprises aprocessor and a pump system for providing a first pump rate and a secondpump rate higher than the first pump rate, and a irrigation system forproviding a variable irrigation rate, the processor configured toautomatically switch from the first pump rate to the second pump rateand vary the irrigation rate according to the pump rates. The pumpsystem may comprise multiple pumps, including a first pump and secondpump.

Yet another embodiment of the invention may include a method forapplying aspiration to a probe. The method may be computer implemented.The method may include applying a aspiration flow-rate first pump to aprobe to achieve a first level flow-rate, tracking a vacuum level tocontrol aspiration of probe, setting a threshold vacuum level, switchingfrom the first level flow-rate to a second level flow-rate from a secondpump, and tracking flow rate to control the aspiration of the probe whenthe threshold vacuum level is passed. The method may include switchingfrom the first pump to a second pump, while maintaining the sameflow-rate.

Yet another embodiment of the invention may include a system forremoving material from within an eye. The system may include a probehaving a distal tip insertable into the eye, wherein the tip comprisesan aspiration port, and a console coupled with/to the port along anaspiration pathway, wherein the console comprises a processor and a pumpsystem for providing a first pump rate and a second pump rate higherthan the first pump rate. Further, the processor is configured toautomatically switch from the first pump rate to the second pump rateand control aspiration of the probe by tracking a vacuum level up to athreshold, and control aspiration of the probe by tracking a flow rateof the probe when the threshold has been passed. The pump system maycomprise multiple pumps, including a first pump and a second pump.

Yet another embodiment of the invention may a include aphacoemulsification system, comprising a handpiece, wherein thehandpiece comprises a needle having at least one port and wherein theneedle is configured to move in a substantially longitudinal and anon-longitudinal direction; a first pump, wherein the first pump isconfigured to operate when a longitudinal cutting mode is selected; anda second pump, wherein the second pump is configured to operate when anon-longitudinal cutting mode is selected. The first pump may comprise aflow based pump and the second pump may comprise a vacuum based pump.Alternatively, the first pump may comprise a vacuum based pump and thesecond pump may comprise a vacuum based pump. Further, thenon-longitudinal direction may be selected from the group consisting oftransversal and torsional. The invention may further comprise a footpedal, wherein the foot pedal is configured to move in a first directionand a second direction, wherein the first direction is configured tocontrol the first pump and the second direction is configured to controlthe second pump. The first direction and the second direction may beselected from the group consisting of yaw and pitch.

To better understand the nature and advantages of the invention,reference should be made to the following description and theaccompanying figures. It is to be understood, however, that each of thefigures is provided for the purpose of illustration only and is notintended as a definition of the limits of the scope of the presentinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exemplary phacoemulsification/vitrectomyirrigation/aspiration system in a functional block diagram to show thecomponents and interfaces for a safety critical medical instrumentsystem that may be employed in accordance with an embodiment of thepresent invention.

FIGS. 2A and 2B are a functional block diagrams of an exemplary surgicalcassette venting systems, according to embodiments of the invention.

FIG. 3 is a functional block diagram illustrating a surgical cassetteventing system configured for venting to a BSS (irrigation) bottle,according to one embodiment of the invention.

FIG. 4 is a functional block diagram illustrating a surgical cassetteventing system configured for peristaltic aspiration operation,according to one embodiment of the invention.

FIG. 5 is a functional block diagram illustrating a surgical cassetteventing system configured for peristaltic venting operation, accordingto one embodiment of the invention.

FIG. 6 is a functional block diagram illustrating a surgical cassetteventing system configured for vacuum regulator aspiration operation,according to one embodiment of the invention.

FIG. 7 is a functional block diagram illustrating a surgical cassetteventing system configured for vacuum regulator venting operation,according to one embodiment of the invention.

FIG. 8 is a graphical depiction of the operation of a surgical system,according to one embodiment of the invention.

FIG. 9A is a flow chart of a method for applying aspiration to a probe,according to one embodiment of the invention.

FIG. 9B is a graphical depiction of the operation of a surgical system,according to one embodiment of the invention.

FIG. 10A is a flow chart of a method for applying aspiration andirrigation to a probe, according to one embodiment of the invention.

FIG. 10B is a graphical depiction of the operation of a surgical system,according to one embodiment of the invention.

FIG. 11A is a flow chart of a method for applying aspiration to a probe,according to one embodiment of the invention.

FIG. 11B is a graphical depiction of the operation of a surgical system,according to one embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates an exemplary phacoemulsification/vitrectomy system100 in a functional block diagram to show the components and interfacesfor a safety critical medical instrument system that may be employed inaccordance with an aspect of the present invention. A serialcommunication cable 103 connects GUI host 101 module and instrument host102 module for the purposes of controlling the surgical instrument host102 by the GUI host 101. GUI host 101 and instrument host 102, as wellas any other component of system 100, may be connected wirelessly.Instrument host 102 may be considered a computational device in thearrangement shown, but other arrangements are possible. An interfacecommunications cable 120 is connected to instrument host 102 module fordistributing instrument sensor data 121, and may include distribution ofinstrument settings and parameters information, to other systems,subsystems and modules within and external to instrument host 102module. Although shown connected to the instrument host 102 module,interface communications cable 120 may be connected or realized on anyother subsystem (not shown) that could accommodate such an interfacedevice able to distribute the respective data.

A switch module associated with foot pedal 104 may transmit controlsignals relating internal physical and virtual switch positioninformation as input to the instrument host 102 over serialcommunications cable 105 (although foot pedal 104 may be connectedwireless, e.g. Bluetooth, IR). Instrument host 102 may provide adatabase file system for storing configuration parameter values,programs, and other data saved in a storage device (not shown). Inaddition, the database file system may be realized on the GUI host 101or any other subsystem (not shown) that could accommodate such a filesystem. The foot pedal system (104) can be configured as dual linear. Inthis configuration, the surgeon can dictate the system to operate withthe peristaltic pump in the traditional pitch and add the venturi vacuumwith the yaw mechanism. This will allow a surgeon the control ofperistaltic operation with the added efficiency of venturi operation.The foot pedal 104 can also combine longitudinal cutting modes with acertain pump and non-longitudinal cutting modes (i.e., transversal,torsion, etc.) with a different pump for example, the foot pedal pitchcould control a peristaltic pump with longitudinal ultrasonic cutting,and the yaw could control the venturi pump with non-longitudinalcutting. The foot pedal can also be configured to operate using acertain pump by yawing to the left and operate a second pump by yawingto the right. This gives the user the ability to switch-on-the-flywithout accessing the user interface which may be timely and cumbersome.Control of one or more pumps may be programmed to the pitch and/or yawdirectional movement of a treadle of foot pedal 104 and/or to any switchlocated on foot pedal 104

The phacoemulsification/vitrectomy system 100 has a handpiece 110 thatincludes a needle and electrical means, typically a piezoelectriccrystal, for ultrasonically vibrating the needle. The instrument host102 supplies power on line 111 to a phacoemulsification/vitrectomyhandpiece 110. An irrigation fluid source 112 can be fluidly coupledwith/to handpiece 110 through line 113. The irrigation fluid andultrasonic power are applied by handpiece 110 to an eye, or affectedarea or region, indicated diagrammatically by block 114. Alternatively,the irrigation source may be routed to eye 114 through a separatepathway independent of the handpiece. Aspiration is provided to eye 114by one or more pumps (not shown), such as a peristaltic pump, via theinstrument host 102, through lines 115 and 116. A surgeon/operator mayselect an amplitude of electrical pulses either using the handpiece,foot pedal, via the instrument host and/or GUI host, and/or by voicecommand.

The instrument host 102 generally comprises at least one processorboard. Instrument host 102 may include many of the components of apersonal computer, such as a data bus, a memory, input and/or outputdevices (including a touch screen (not shown)), and the like. Instrumenthost 102 will often include both hardware and software, with thesoftware typically comprising machine readable code or programminginstructions for implementing one, some, or all of the methods describedherein. The code may be embodied by a tangible media such as a memory, amagnetic recording media, an optical recording media, or the like. Acontroller (not shown) may have (or be coupled with/to) a recordingmedia reader, or the code may be transmitted to instrument host 102 by anetwork connection such as an internet, an intranet, an Ethernet, awireless network, or the like. Along with programming code, instrumenthost 102 may include stored data for implementing the methods describedherein, and may generate and/or store data that records parametersreflecting the treatment of one or more patients.

In combination with phacoemulsification system 100, the present systemenables aspiration, venting, or reflux functionality in or with thephacoemulsification system and may comprise components including, butnot limited to, a flow selector valve, two or more pumps, a reservoir,and a collector, such as a collection bag or a device having similarfunctionality. The collector in the present design collects aspirantfrom the ocular surgical procedure.

FIG. 2A illustrates an exemplary surgical cassette system in afunctional block diagram that shows the components and interfaces thatmay be employed in accordance with an aspect of the present design. Anirrigation source 46 of, and/or controlled by, instrument host 102optionally provides irrigation fluid pressure control via an irrigationline 51 by relying at least in part on a gravity pressure head thatvaries with a height of an irrigation fluid bag or the like. Anirrigation on/off pinch valve 48 may generally include a short segmentof a flexible conduit of cassette 16A, which can be engaged and actuatedby an actuator of the instrument host 102, with a surface of thecassette body often being disposed opposite the actuator to facilitateclosure of the conduit lumen. Alternative irrigation flow systems mayinclude positive displacement pumps, alternative fluid pressurizationdrive systems, fluid pressure or flow modulating valves, and/or thelike.

In certain embodiments, irrigation fluid is alternatively oradditionally provided to a separate handpiece (not shown). Theaspiration flow network 50 generally provides an aspiration flow path 52that can couple an aspiration port in the tip of handpiece 110 to eithera peristaltic pump 54, formed by engagement of cassette 16A withinstrument host 102, and/or a holding tank 56. Fluid aspirated throughthe handpiece 110 may be contained in holding tank 56 regardless ofwhether the aspiration flow is induced by peristaltic pump 54 or thevacuum applied to the holding tank 56 via pump 57. When pinch valve 58is closed and peristaltic pump 54 is in operation, pumping of theaspiration flow may generally be directed by the peristaltic pump 54,independent of the pressure in the holding tank 56. Conversely, whenperistaltic pump 54 is off, flow through the peristaltic pump may behalted by pinching of the elastomeric tubing arc of the peristaltic pumpby one or more of the individual rollers of the peristaltic pump rotor.Hence, any aspiration fluid drawn into the aspiration network whenperistaltic pump 54 is off will typically be effected by opening of apinch valve 58 so that the aspiration port of the probe is in fluidcommunication with the holding tank. Regardless, the pressure withintank 56 may be maintained at a controlled vacuum level, often at a fixedvacuum level, by a vacuum system 59 of instrument host 102.

Vacuum system 59 may comprise a Venturi pump 57, a rotary vane pump, avacuum source, a vent valve 44, a filter and/or the like. Aspirationflow fluid that drains into holding tank 56 may be removed by aperistaltic drain pump 60 and directed to a disposal fluid collectionbag 62. Vacuum pressure at the surgical handpiece 110 may be maintainedwithin a desired range through control of the fluid level in the holdingtank. In particular, peristaltic drain pump 60 enables the holding tank56 to be drained including, while vacuum-based aspiration continuesusing vacuum system 59. In more detail, the operation of aspiration flownetwork 50 can be understood by first considering the flow when pinchvalve 58 is closed. In this mode, peristaltic pump 54 draws fluiddirectly from handpiece 110, with a positive displacement peristalticpump flow rate being controlled by a system controller. To determine theappropriate flow rate, the level of vacuum within the aspiration flownetwork may be identified in part with reference to a vacuum sensor 64with three ports disposed along the aspiration flow network 50 betweenperistaltic pump 54, handpiece 110, and pinch valve 58. This allows thesystem to detect and adjust for temporary occlusions of the handpiece110 and the like. Venting or reflux of the handpiece 110 in this statemay be achieved by reversing the rotation of peristaltic pump 54 or byopening pinch valve 58 to equalize fluid pressures. Pinch valve 58 maybe configured as a variable restrictor to regulate the amount of fluidthat is vented and/or refluxed from the high pressure side ofperistaltic pump 54 to the low pressure side. In this mode, while theaspiration material flows through holding tank 56 and eventually intocollection bag 62, the holding tank pressure may have little or noeffect on the flow rate. When peristaltic pump 54 is not in operation,rotation of the peristaltic pump may be inhibited and the rotors of theperistaltic pump generally pinch the arcuate resilient tubing of theprobe so as to block aspiration flow. Material may then be drawn intothe aspiration port of handpiece 110 by opening pinch valve 58 andengagement or operation of the vacuum system 59. When valve 58 is open,the aspiration port draws fluid therein based on the pressuredifferential between holding tank 56 and the chamber of the eye in whichthe fluid port is disposed, with the pressure differential being reducedby the total pressure loss of the aspiration flow along the aspirationpath between the tank and port. In this mode, venting or reflux of thehandpiece 110 may be accomplished by opening the solenoid vent valve 44,which pressurizes the holding tank 56 to increase the tank pressure andpush fluid back towards (i.e., “vents”) the tubing and/or handpiece 110.

In some embodiments, the vent valve 44 may be used to increase thepressure inside the tank 56 to at or near atmospheric pressure.Alternatively, venting of the handpiece 110 may be accomplished in thismode by closing pinch valve 58, and by rotation peristaltic pump 54 inreverse (e.g., clockwise in FIG. 2A). Accordingly, aspiration network 50allows system 100 to operate in either flow-based (e.g. peristaltic)and/or vacuum-based (e.g. Venturi) pumping modes and to incorporatethree different venting modes. In some embodiments, an additional valveis added that may be used to fluidly couple the irrigation line 51 tothe aspiration flow network 50, thus providing an addition option forventing or refluxing the handpiece 110.

FIG. 2B illustrates another exemplary surgical cassette system in afunctional block diagram that shows the components and interfaces thatmay be employed in accordance with an aspect of the present design.

The present design effectively splits the aspiration line from handpiece110 into at least two separate fluid pathways where one is connected tocollector 206 and the other to the air/fluid reservoir 204, which isalso connected to collector 206. Splitting the fluid pathways in thisway allows one line designated for vacuum regulated aspiration, venting,and/or reflux and the other line designated for peristaltic aspiration,venting, and/or reflux. However, the aspiration line, or the at leasttwo separate fluid pathways may be connected with air/fluid reservoir204. The vacuum regulated aspiration line 226 connects to reservoir 204,wherein fluid may be aspirated, vented, and/or refluxed to or fromreservoir 204 through the line 226. The peristaltic line connectsdirectly to the collector and aspirates, vents, and/or refluxes throughthe aspiration line 223, 225 without requiring a connection to reservoir204.

Surgical cassette venting system 200 may include a fluid vacuum sensor201, flow selector valve 202, reservoir 204, collector 206, and fluidpathways, such as interconnecting surgical tubing, as shown in FIG. 2B.The cassette arrangement 250 may include connections to facilitate easyattachment to and removal from the instrument host 102 as well ashandpiece 110 and vacuum pump arrangement 207. The present designcontemplates two or more pumps, where the surgical cassette arrangementmay operate with fluid pathways or other appropriate fluidinterconnections interfacing with the two or more pumps.

Cassette arrangement 250 is illustrated in FIG. 2B to simply showcomponents that may be enclosed within the cassette. The size and shapeof cassette 250 is not to scale nor accurately sized, and note thatcertain components, notably peristaltic pump 203, interface with thecassette but in actuality form part of the device which the cassetteattaches to. Further, more or fewer components may be included in thecassette than are shown in FIGS. 2A and 2B depending on thecircumstances and implementation of the cassette arrangement 250.

Referring to FIG. 2B, handpiece 110 is connected to the input side offluid vacuum sensor 201, typically by fluid pathways such as fluidpathway 220. The output side of fluid vacuum sensor 201 is connected toflow selector valve 202 within cassette arrangement 250 via fluidpathway 221. The present design may configure flow selector valve 202 tointerface between handpiece 110, balanced saline solution (BSS) fluidbottle 112, pump 203, which is shown as a peristaltic pump but may beanother type of pump, and reservoir 204. In this configuration, thesystem may operate flow selector valve 202 to connect handpiece 110 withBSS fluid bottle 112, reservoir 204 or with pump 203 based on signalsreceived from instrument host 102 resulting from the surgeon's input toGUI host 101.

The flow selector valve 202 illustrated in FIG. 2B provides a singleinput port and may connect port ‘0’ to one of three available portsnumbered ‘1’, ‘2’, and ‘3’. The present design is not limited to oneflow selector valve, and may be realized using two flow selector valveseach having at least two output ports, possibly connected together toprovide the functionality described herein. For example, a pair of twooutput port valves may be configured in a daisy chain arrangement, wherethe output port of a first valve is directly connected to the input portof a second valve. The instrument host may operate both valves togetherto provide three different flow configurations. For example, using twovalves, valve one and valve two, valve one may use output port one,which is the supply for valve two. Valve two may connect to one of twoports providing two separate paths. When valve one connects its inputport to its second output port rather than the output port that directsflow to the second valve, a third path is provided.

Thus while a single flow selector valve 202 is illustrated in FIG. 2B,it is to be understood that this illustration represents a flow selectorvalve arrangement, including one or more flow selector valves performingthe functionality described herein, and is not limited to a singledevice or a single flow selector valve. It is also contemplated thatflow selector valve 202 may be a pinch valve or multiple pinch valves asshown in FIG. 2A, and for example as shown in co-assigned U.S. patentapplication Ser. No. 11/937,456, the entirety of which is incorporatedby reference herein. It is also contemplated that flow selector valve202 and fluid vacuum sensor 201 may be a single unit, e.g. fluid vacuumsensor 201 may comprise or be a part of flow selector valve 202.

It is also envisioned that flow selector valve 202 may be or compriseone or more pinch valves. The one or more pinch valves may be locatedalong fluid pathway 221 and/or 223, or any other fluid pathway asdiscussed herein. Further, there may be one or more fluid pathwayscouples with handpiece 110 and extending to various components ofcassette arrangement 250, including a first fluid pathway from fluidvacuum sensor 201 to collector 206 via pump 203 and/or a second fluidpathway to reservoir 204. In another embodiment, fluid pathway 220 is asingle fluid pathway that couples with fluid vacuum sensor 201. Fromfluid vacuum sensor 201, the single fluid pathway 220 may divide intotwo fluid pathways, one to collector 206 via pump 203 and one toreservoir 204. Further, one or more pinch valves and/or flow selectorvalve 202 may be located along the fluid pathway between fluid vacuumsensor 201 and collector 206 and/or between fluid vacuum sensor 201 andreservoir 204.

The present design's fluid vacuum sensor 201, for example a strain gaugeor other suitable component, may communicate or signal information toinstrument host 102 to provide the amount of vacuum sensed in thehandpiece fluid pathway 220. Instrument host 102 may determine theactual amount of vacuum present based on the communicated information.

Fluid vacuum sensor 201 monitors vacuum in the line, and can be used todetermine when flow should be reversed, such as encountering a certainpressure level (e.g. in the presence of an occlusion), and based onvalues obtained from the fluid vacuum sensor 201, the system may controlselector valve 202 and the pumps illustrated or open the line to refluxfrom irrigation. It is to be understood that while components presentedin FIG. 2B and other drawings of the present application are not shownconnected to other system components, such as instrument host 102, butare in fact connected for the purpose of monitoring and control of thecomponents illustrated. Flow selector valve 202 and fluid vacuum sensor201 may also exist as a single unit.

With respect to fluid vacuum sensor 201, emergency conditions such as adramatic drop or rise in pressure may result in a type of fail-safeoperation. The present design employs fluid vacuum sensor 201 to monitorthe vacuum conditions and provide signals representing vacuum conditionsto the system such as via instrument host 102 for the purpose ofcontrolling components shown including, but not limited to flow selectorvalve 202 and the pumps shown. Alternative embodiments may include flowsensors (not shown).

Multiple aspiration and ventilation options are available in the designof FIG. 2B. In the arrangement where the selector valve 202 connectshandpiece 110 with BSS bottle 112, the present design allows for ventingof fluid from BSS bottle 112 to eye 114 as indicated by directional flowarrow ‘Z’ 236 and arrow ‘A’ 222 in FIG. 2B. In the arrangement where theflow selector valve 202 connects handpiece 110 with peristaltic pump203, the present design may allow for aspiration from eye 114 directlyto collector 206 as indicated by flow indicated in the directions of ‘X’238, arrow B 242, and arrow E at 232 as illustrated in FIG. 2B.Reversing direction of pump 203 can result in venting and/or refluxing.

In the arrangement where the cassette system flow selector valve 202connects handpiece 110 with reservoir 204, the present design allows foraspiration from eye 114 directly to reservoir 204 as indicated bydirectional flow arrow ‘X’ 238, and arrow C 240 in FIG. 2B.Arrows/directions 238, 242, and 232 illustrate the flow of fluid forperistaltic pumping. Arrow 224 indicates the direction of operation forperistaltic pump 203 where fluid originating at handpiece 110 is pumpedthrough line 223 toward line 225 during aspiration. Arrows/directions238 and 240 illustrate the flow of fluid for venturi pumping.

Although venting is shown from BSS bottle 112, venting and/or irrigationis not represented in FIG. 2B via the pumps. However, the present designmay allow for venting and/or reflux using the pumps associated with thecassette where the arrows in FIG. 2B are reversed; for example,indicating pump 203 is reversed or operates in a counter-clockwisedirection. In this arrangement, the design may effectively split theaspiration line from the handpiece into two distinct lines, one arrangedfor peristaltic operation and the second line arranged for vacuumregulated operation via an air/fluid reservoir.

Reservoir 204 may contain air in section 211 and fluid in section 212.Surgical cassette system 200 may connect reservoir 204 with collector206 using fluid pathways, such as surgical tubing or similar items. Inthis arrangement, pump 205 may operate in a clockwise direction in thedirection of arrow 228 to remove fluid from the reservoir 204 throughfluid pathway 227 and deliver the fluid to collector 206 using fluidpathway 229. The present design illustrates a peristaltic pump as pump205, a component within instrument host 102, but other types of pumpsmay be employed. This configuration may enable the surgical cassette 200to remove unwanted fluid and/or material from reservoir 204.

The fluid pathways or flow segments of surgical cassette system 200 mayinclude the fluid connections, for example flexible tubing, between eachcomponent represented with solid lines in FIG. 2B.

Vacuum pump arrangement 207 is typically a component within instrumenthost 102, and may be connected with reservoir 204 via fluid pathway orflow segment 230. In the configuration shown, vacuum pump arrangement207 includes a pump 208, such as a venturi pump and an optional pressureregulator 209 (and valve (not shown)), but other configurations arepossible. In this arrangement, vacuum pump arrangement 207 may operateto remove air from the top of reservoir 204 and deliver the air toatmosphere (not shown). Removal of air from reservoir 204 in this mannermay reduce the pressure within the reservoir, which reduces the pressurein the attached fluid pathway 226, to a level less than the pressurewithin eye 114. A lower reservoir pressure connected through flowselector valve 202 may cause fluid to move from the eye, therebyproviding aspiration. The vacuum pump arrangement 207 and reservoir 204can be used to control fluid flow into and out of reservoir 204. Vacuumpump arrangement 207 may also be used to vent the aspiration line to airby opening a valve to the venturi pump.

The optional pressure regulator 209 may operate to add air to the top ofreservoir 204 which in turn increases pressure and may force theair-fluid boundary 213 to move downward. Adding air into reservoir 204in this manner may increase the air pressure within the reservoir, whichincreases the pressure in the attached fluid aspiration line 226 to alevel greater than the pressure within eye 114. A higher reservoirpressure connected through flow selector valve 203 may cause fluid tomove toward eye 114, thereby providing venting or reflux.

An alternate method of creating positive pressure in reservoir 204 isrunning pump 205 in a counter-clockwise direction. Running pump 205 in acounter-clockwise direction will increase the amount of air in section211 in reservoir 204.

It is to be noted that higher pressure in reservoir 204 causes morefluid flow and potentially more reflux from reservoir 204 to handpiece110. If the lines from the reservoir 204 are plugged or otherwiseoccluded, providing pressure to reservoir 204 can result in ventingand/or reflux. Venting in this context results in the release ofpressure. Reflux occurs when a pump is reversed sending fluid in theopposite direction of normal flow (e.g. toward the eye). In a refluxcondition, the surgeon can control the amount of fluid flowing backthrough the fluid pathways and components.

The present design may involve peristaltic operation, aspirating fluidfrom eye 114 to collector 206 illustrated in FIG. 2B, or venting fluidto the eye 114 to reduce the amount of pressure in the aspiration line(where such venting is only shown from BSS bottle 112 in FIG. 2).Peristaltic pumping is generally understood to those skilled in the art,and many current machines employ peristaltic and/or venturi pumps as thevacuum or pressure sources. Generally, a peristaltic pump has fluidflowing through a flexible tube and a circular rotor with a number ofrollers attached to the periphery of the circular rotor. As the rotorturns, fluid is forced through the tube. Venturi pumping, or pressure oraspiration or aspirator pumping, produces the vacuum using the venturieffect by providing fluid through a narrowing tube. Because of thenarrowing of the tube, the speed at which the fluid travels through thetube increases and the fluid pressure decreases (the “Venturi effect”).As may be appreciated, operating pumps in one direction or another canchange the pressure and the operation of the associated device, such asthe operation of the cassette in the present design.

FIG. 3 is a functional block diagram illustrating a surgical cassettesystem configured for venting using a balanced saline solution (BSS)bottle in accordance with an aspect of the present design.

In the arrangement where the flow selector valve 202 connects handpiece110 with BSS bottle 112, the present design may allow for venting offluid to eye 114 directly from BSS bottle 112 and/or the line betweenflow selector valve 202 and BSS bottle 112, where fluid from BSS bottle112 and/or the line flows toward and through flow selector valve 202.The fluid flow continues to flow toward and through flow selector valve202 in the direction indicated by arrow 321. In order to vent from BSSbottle 112, instrument host 102 may signal flow selector valve 202 toconnect port ‘0’ to port ‘1’. When the flow selector valve 202 switchesto position ‘1,’ fluid may flow from BSS bottle 112 and/or the linebetween BSS bottle 112 and flow selector valve 202 to handpiece 110 asindicated by directional arrows 322 and 321 as shown in FIG. 3. Duringfluid venting from bottle 112 and/or the line between BSS bottle 112 andflow selector valve 202, the present design may arrange the bottleposition at an elevated height relative to the eye 114, thus realizing apositive pressure source.

FIG. 4 is a functional block diagram illustrating a surgical cassettesystem 400 configured for normal peristaltic aspiration. The presentdesign may configure flow selector valve 202 to connect handpiece 110 topump 203 and may operate selector valve 202 to connect fluid pathway 421at port ‘0’ to fluid pathway 422 at port ‘3’ of flow selector valve 202.In this aspiration configuration, reservoir 204 is not employed. As pump203 operates in a clockwise direction to pump fluid in the directionshown by arrow 424, the present design aspirates fluid from eye 114 tocollector 206 following the path formed by connecting fluid pathway 420from the handpiece to fluid vacuum sensor 201, continuing through fluidpathway 421 toward the flow selector valve 202 where a fluid line isconnected from flow selector valve 202 to pump 203 and moving fluid inthe direction shown by the arrow above fluid pathway 422. Clockwise pumpoperation shown by arrow 423 forces fluid into fluid pathway 425 indirection 424 toward collector 206. During an ocular procedure, thesurgeon may stop the flow of fluid into the eye by stopping pump 203.When pump 203 is stopped, the rollers within the peristaltic pump stopmoving and fluid through this path ceases to move or flow.

FIG. 5 illustrates a surgical cassette system 500 configured for ventingand reflux operation. The present design may configure flow selectorvalve 202 to connect handpiece 110 to pump 203 from port ‘3’ to port‘0’. As the pump 203 operates in a counter-clockwise direction as shownby arrow 523, the present design may vent fluid through fluid pathway525 in direction of flow arrows at 524, 523, 522, and 521 and ultimatelyto fluid pathway 220. Note that in both FIGS. 4 and 5, flow selectorvalve 202 neither operates to take fluid from nor output fluid toreservoir 204.

In the configuration of FIG. 5, the system can stop the inflow of fluidfrom fluid pathway 525 to the eye by stopping pump 203 or closing flowselector valve 202, or both. The internal volume of fluid pathway 525has sufficient fluid volume to provide venting and/or reflux.

The present design may alternately employ vacuum pump arrangement 207 toaspirate fluid from eye 114 to reservoir 204 as illustrated in FIG. 6,or applying pressure thus forcing fluid from reservoir 204 throughselector valve 202 and irrigating eye 114 as illustrated in FIG. 7.

FIG. 6 is a functional block diagram illustrating the system configuredfor vacuum pump arrangement 207 aspiration operation where the presentdesign may operate either in a normal venturi aspiration mode to createa vacuum at fluid pathway 626. Again, flow selector valve 202 connectshandpiece 110 with reservoir 204 from port ‘2’ to port ‘0’. In thisaspiration configuration, pump 203 is not in use and typically notoperating. Vacuum pump arrangement 207 may operate to allow pressure tobe removed from reservoir 204 either by venting to atmosphere or drawinga vacuum. Removing or reducing pressure using vacuum pump arrangement207 may move air-fluid boundary 213 upward at 645 to aspirate fluid fromeye 114 to reservoir 204. Again, vacuum pump arrangement 207 may includeor be attached to a venturi pump or pumping device. The fluid path fromeye 114 to reservoir 204 follows the direction indicated by the arrowsabove fluid passageway 621 and to the right of fluid passageway 626.Optionally, to vent and/or reflux, pressure regulator 209 may be used toincrease the pressure in reservoir 204 to cause fluid to flow throughfluid pathway 626 toward handpiece 110 via flow selector valve 202.

FIG. 7 is a functional block diagram illustrating a surgical cassettesystem 700 configured for venting and/or reflux operation in accordancewith an aspect of the present invention. The present design mayconfigure flow selector valve 202 to connect handpiece 110 withreservoir 204 from port ‘2’ to port ‘0’. Vacuum pump arrangement 207 mayoperate to provide pressure to reservoir 204 via pressure regulator 209.Applying or increasing pressure using pressure regular 209 of vacuumpump arrangement 207 may move air-fluid boundary 213 downward in thedirection of 745 causing fluid to flow from reservoir 204 and/or fluidpathway 726 to eye 114.

In sum, the present design surgical cassette system provides foraspiration, venting, and/or reflux using pumping operations. A pluralityof pumps are typically employed, including a first pump and a secondpump, where a first pump may be pump 203, shown as a peristaltic pump inFIG. 2B, and pump 208, representing a venturi pump in certainembodiments shown herein.

The instrument host 102 may provide a signal to position or switch flowselector valve 202 for desired peristaltic or vacuum regulatedoperation. Aspiration, venting, and/or reflux may be controlled invarious ways, including but not limited to switching offered to thesurgeon on the instrument host 102, switching via a switch such as oneprovided on handpiece 110 or via a footswitch, or via automatic orsemi-automatic operation, wherein pressure is sensed at some point, suchas coming from the handpiece to the instrument host at sensor 201 orseparately sensed by a sensor placed in the ocular region with pressuresignals being provided to the instrument host 102. In general, automaticor semi-automatic operation entails sensing a drop or rise in pressureand either aspirating fluid to or venting fluid from the ocular regionor eye 114. In any circumstance, the surgeon or other personnel areprovided with the ability to run the pumps in any available direction,such as for cleaning purposes.

Other pumping states may be provided as discussed herein and based onthe desires of personnel performing the surgical procedure. For example,in the case of the surgeon desiring aspiration operation as shown inFIG. 6 in all circumstances as opposed to aspiration as shown in FIG. 4,the surgeon may enable settings or the instrument host may provide forthe surgeon to select such operation. Additionally, if the surgeonbelieves venturi pumping or vacuum regulator operation should beemployed wherever possible, she may select that from the instrumenthost. Other configurations may be provided, including limiting ocularpressure within a desired range, and so forth.

Certain additional functionality or components may be provided in thecurrent design. For example, a valve (not shown) may be located betweenpump 203 and flow selector valve 202 or between pump 203 and handpiece110 in the design, such as in the design of FIG. 3, to build a bolus offluid or build pressure between the valve and pump 203. Such a valve canthereby create positive pressure when pump 203, such as a peristalticpump, reverses direction of flow and provides pressure to the valve.This positive pressure can be released by opening the valve therebyventing the system.

Referring to FIG. 1, the instrument host 102 will generally include atleast one processor for processing instructions and sending commandsignals to other components of the system, and memory for storinginstructions. The instrument host 102 and GUI host may be housed in aconsole. The instructions generally include methods for operating thesystem 100. Methods disclosed herein may be stored as instructions onthe memory.

FIG. 8 shows a graph 802 which depicts a system switching from a firstpump to a second pump according to one embodiment of the invention. Thesystem may be the system 100 depicted in FIG. 1. Curve V_(I) shows theoperation of the first pump in terms of aspiration level (which may beflow-rate or vacuum level) versus time T. The first pump may be avolumetric, e.g. peristaltic or other displacement, pump. The first pumpis capable of attaining a limited aspiration level, as shown. CurveP_(I) shows the operation of the second pump in terms of aspirationlevel versus time T. The second pump may be a pressure, e.g. venturi orother pressure differential, pump and capable of a higher aspirationlevel than the first pump. As shown, through cassette arrangement 250,the second pump may begin operation while the first pump is operating atits maximum aspiration level, and thus a transitional time T_(R) betweenthe peak aspiration levels is constantly increasing. Note that the timefor initiating of a newly energized pump may occur before, during, orafter a start time of the ramp-down or decreasing of aspiration flowfrom a previously operating pump. Similarly, a complete halt of flow orend of the ramp-down may occur before, during or after the end of theramp-up, so that the transitions shown schematically herein aresimplified. Also, the ramp-up and ramp-down of aspiration may moreaccurately be represented by curves (rather than single linear slopes).Nonetheless, the ramp-up of the newly employed pump (the second pump)will typically start before the ramp-down of the first pump has beencompleted. Thus, there is typically no time delay between switching ofthe pumps. Automatic switching between pumping systems, without the needfor user interaction may be applied by automated control of the flowselector valve 202. Switching may occur as a series of cycles or pulses,and thus occur over a very short period of time, in some examples havinga frequency of a few milliseconds, less than a second, and/or a fewseconds. A user may preprogram how and/or when switching betweenmultiple pumps occurs.

FIG. 9A shows a method 900 for applying aspiration to an eye using aprobe (e.g. handpiece), according to one embodiment of the invention.Method 900 may be employed on the system 100 shown in FIG. 1. Whensolely using a pressure pump (e.g. a venturi/vacuum-type pump) toaspirate an eye, it may be difficult to detect when the probe isoccluded by sensing vacuum changes when using a pressure pump. This isbecause the pressure pump may be configured to automatically compensatefor pressure level, and thus no detectable pressure change is available.Method 900 tracks pressure changes from a secondary pump, which may be avolumetric pump, to detect occlusions while in a high flow-rateaspiration mode. At operation 902 a first pump, operating at a highflow-rate (e.g. high vacuum-rate), aspirates via a probe which is in aregion of an eye. The probe for example may be a phacoemulsificationdevice or a vitrectomy device. The first pump may be a pressure, e.g.venturi, pump. At operation 904 a second pump, operating at a low-flowrate, also aspirates via the probe. The second pump may be a volumetricpump, e.g. a peristaltic pump. At operation 906 the vacuum level, orpressure differential, of the second pump is monitored. As shown inoperation 908, if a vacuum change is not detected via a pressure sensoror similar device, then the vacuum level is continuously monitored. If avacuum change is detected, for example by an increased pressuredifferential above a base pressure differential, then the probe may bedetermined to be at least partially occluded and thus in contact withcataract tissue, as shown in operation 910. Detection of theocclusion-induced pressure change may be facilitated by altering orinhibiting operation of the pressure-regulating system of the venturipump in some modes, such as by the use of a check valve to avoid refluxflow from the venturi pump toward the pressure sensor of the cassette.

Phacoemulsification probes often work optimally when sufficientlyoccluded, as the ultrasonically energized tip will then be engaged withthe tissue targeted for fragmentation. Thus, the determination that theprobe is at least partially occluded may follow with an application of,change and/or adjustment of ultrasonic energy to the probe.Additionally, the first pump may be instructed to be switched off, sothat aspiration is performed by the second pump only.

FIG. 9B shows a graphical depiction of method 900 shown in FIG. 9A,according to one embodiment of the invention. Curves 912 and 914 showthe aspiration flows of the first pump and second pump, respectively.Curve 916 shows the pressure differential, which is detected from thesecond pump, which may be a peristaltic pump. Curve dips 912A and 914Aindicate that the probe has been at least partially occluded, resultingin a reduced aspiration rate. Simultaneously, an increased pressuredifferential, shown by curve increase 916A, shows a detectable response.Accordingly, the increase pressure differential may be used to sendcommand signals to various portions of the system.

FIG. 10A shows a method 1000 for applying aspiration to an eye using aprobe, according to one embodiment of the invention. Method 1000 may beemployed on the system 100 shown in FIG. 1. At operation 1010 a firstpump, operating at a low flow-rate, aspirates via a probe which is in aregion of an eye. The first pump may be a volumetric, e.g. peristaltic,pump. Additionally, irrigation is also being supplied to the eye usingthe probe. Irrigation may be provided, for example by irrigation fluidsource 112. At operation 1020 an input is received to switch to a secondpump, and increase the aspiration via the probe and also to increaseirrigation. The second pump may be a pressure pump (e.g. venturi pump).The signal may be automatically triggered by a command signal generatedin response to a detected condition, for example by detecting that theprobe is not sufficient occluded to provide ultrasonic energy tocataract tissue (often per pressure signals generated along theaspiration pathway). The signal may also be manually triggered by a userinput, for example through the actuation of a foot switch. Various meansmay be employed to increase the irrigation rate, for example a fluidsource may be automatically placed at a higher position and/orpressurized infusion may be used. An example of this is shown inco-assigned U.S. patent application Ser. No. 11/937,640, the entirety ofwhich is incorporated by reference herein. The fluid source may also bea bagged fluid source and additional pressure, externally or internally,may be automatically applied to increase the irrigation rate. Examplesof this are shown in U.S. Pat. No. 6,491,661, the entirety of which isincorporated by reference herein. Additionally, some examples of factorswhich should be taken into consideration when supplying automaticirrigation are phacoemulsification device tip size, and surgicaltechnique. These factors may be inputted into the console forconsideration by the processor. Thus, fluidic settings (vacuum,aspiration levels) can be limited based on the irrigation level, tipgage, and surgical technique. At operation 1030 it is determined ifwhether the increased aspiration rate will exceed the maximum irrigationrate, which would be an undesirable condition as the eye may be removedof all fluid. At operation 1040, if the increased aspiration rateexceeds the maximum irrigation rate, then the aspiration rate will beautomatically decreased to match the irrigation rate, resulting in abalanced fluid supply condition in the eye. At operation 1050, if theincreased aspiration rate does not exceed the maximum irrigation rate,then the aspiration and irrigation rates will increase according to theinput of operation 1020. Additionally, if the system detects that theprobe has been occluded, resulting in decreased aspiration, theirrigation rate may be reduced automatically to match.

FIG. 10B shows a graphical depiction of method 1000, shown in FIG. 10A,according to one embodiment of the invention. Curves 1060 and 1070 showthe aspiration flows of the first pump and second pump, respectively.Curve 1080 shows the irrigation flow rate supplied to the probe. Atcurve portion 1080A the irrigation flow rate is increased to match theincreased aspiration rate of the second pump. At curve portion 1080B,the irrigation flow rate is shown at its maximum possible flow rate.Curve portion 1070 shows that the maximum aspiration rate has exceededthe maximum irrigation rate, and thus the aspiration rate isautomatically decreased to compensate, as shown in curve portion 1070A.

FIG. 11A shows a method 1100 for applying aspiration to an eye using aprobe, according to one embodiment of the invention. Method 1100 may beemployed on system 100 shown in FIG. 1. In some dual-pump systems,tracking vacuum level for control feedback means does not apply inequivalent terms to each pump. For example, 500 mmHg of vacuum detectedduring the operation of a peristaltic pump may result in an aspirationrate which is far lower than that for 500 mmHg detected during theoperation of a venturi pump. Accordingly, using the same measurement forcontrol feed back for each pump may result in a dangerous condition,e.g. the eye running out of fluid and chamber collapse. At operation1110 a first pump, operating at a low flow-rate, aspirates through aprobe which is in a region of an eye. The first pump may be avolumetric, e.g. peristaltic, pump. The vacuum created by the aspirationis tracked to provide feed back control aspects of the probe operationand aspiration. At operation 1120 a threshold is set for a maximumvacuum level which is used for feedback control purposes. Although onlyone threshold is shown, there may be multiple thresholds set for one,two, or both pumps. At operation 1130, aspiration through the probe isswitched to a second pump, which increases the aspiration rate to theprobe. The second pump may be a pressure pump (e.g. venturi pump). Atoperation 1140 it is determined whether the threshold has been passed.If the threshold has not been passed, then the method 1100 loops back tooperation 1130. If the threshold has been passed, the system switches tocontrol the probe based on flow rate, which may be calculated from knownand measured quantities, some examples including tip size, type ofprocedure, irrigation flow rate, pressure differentials, and actual flowrate. The same flow rate should be at least initially matched whenswitching between pumps. Multiple thresholds may be programmed for oneor more pumps and/or thresholds may be programmed for a combination ofpumps. However, measuring flow rate from a flow meter may be difficultbecause of the interaction of cataract particles with a flow meter.

FIG. 11B shows a graphical depiction of method 1100, shown in FIG. 11A,according to one embodiment of the invention. Curves 1160 and 1170 showthe aspiration flows of the first pump and second pump, respectively.Curve portion 1190 shows the vacuum being tracked for control feedbackof the probe. Dotted line 1180 shows the threshold vacuum level. Curveportion 1190A shows that the threshold has been passed, and accordinglythe system will switch from vacuum feedback based controls to flow-ratebased controls.

The methods and devices disclosed herein may also be used utilized withco-assigned and concurrently filed U.S. Provisional Patent ApplicationNo. 61/198,658, entitled AUTOMATICALLY PULSING DIFFERENT ASPIRATIONLEVELS TO AN OCULAR PROBE, which is incorporated by reference herein inits entirety.

It should be noted that the examples disclosed herein may describelow-flow rate pumps as peristaltic pumps, and high flow-rate pumps asventuri pumps. These are merely examples and are not limiting to theembodiments disclosed herein, for example high-flow rate peristalticpumps may be used in lieu of high flow-rate venturi pumps, and lowflow-rate venturi pumps may be used in lieu of low-flow rate pumpsperistaltic pumps. Additionally, a low flow-rate venturi pump may beused in conjunction with a high flow-rate venturi pump, and a lowflow-rate peristaltic pump may be used in conjunction with a highflow-rate peristaltic pump.

As will be understood by those skilled in the art, the present inventionmay be embodied in other specific forms without departing from theessential characteristics thereof. Those skilled in the art willrecognize, or be able to ascertain using no more than routineexperimentation, many equivalents to the specific embodiments of theinvention described herein. Such equivalents are intended to beencompassed by the following claims.

What is claimed is:
 1. A system for removing material from within aneye, the system comprising: a probe having a distal tip insertable intothe eye, wherein the distal tip comprises an aspiration port; a consolecoupled with the aspiration port along an aspiration pathway, whereinthe console comprises a processor and a pump system for providing afirst pump rate via a first pump and a second pump rate via a secondpump that is higher than the first pump rate; and wherein the processoris configured to automatically switch from the first pump rate to thesecond pump rate, to begin a ramp-up of the second pump before aramp-down of the first pump such that a flow rate while providing thefirst pump rate is matched to a flow rate when switching from the firstpump rate to the second pump rate, to control aspiration through theprobe by tracking a vacuum level up to a threshold, and to controlaspiration through the probe by tracking a flow rate through the probewhen the threshold has been passed.
 2. The system of claim 1, whereinthe probe comprises a phacoemulsification probe.
 3. The system of claim1, wherein the probe comprises a vitrectomy probe.
 4. The system ofclaim 1, wherein the first pump is a peristaltic pump and the secondpump is a venturi pump.
 5. The system of claim 1, wherein the thresholdpasses while the second pump rate is provided.
 6. A method for removingmaterial from within an eye, the method comprising: aspirating an eyewith a probe using a first pump at a first pump rate and tracking avacuum differential to control aspiration through the probe; setting athreshold vacuum level; automatically switching from the first pump toaspirating the eye with a second pump at a second pump rate higher thanthe first pump rate, wherein a ramp-up of the second pump starts beforea ramp-down of the first pump such that a flow rate during the switch ismatched; determining that the threshold vacuum level has been passed;and controlling aspiration through the probe by tracking a flow ratethrough the probe, based on determining that the threshold vacuum levelhas been passed.
 7. The method of claim 6, wherein the probe comprises aphacoemulsification probe.
 8. The method of claim 6, wherein the probecomprises a vitrectomy probe.
 9. The method of claim 6, wherein thefirst pump is a peristaltic pump and the second pump is a venturi pump.10. The method of claim 6, wherein the threshold vacuum level passeswhile the second pump rate is provided.